+
+/**
+ * Convert GL_LINE_LOOP primitive into GL_LINE_STRIP so that drivers
+ * don't have to worry about handling the _mesa_prim::begin/end flags.
+ * See https://bugs.freedesktop.org/show_bug.cgi?id=81174
+ */
+static void
+convert_line_loop_to_strip(struct vbo_save_context *save,
+ struct vbo_save_vertex_list *node)
+{
+ struct _mesa_prim *prim = &node->prims[node->prim_count - 1];
+
+ assert(prim->mode == GL_LINE_LOOP);
+
+ if (prim->end) {
+ /* Copy the 0th vertex to end of the buffer and extend the
+ * vertex count by one to finish the line loop.
+ */
+ const GLuint sz = save->vertex_size;
+ /* 0th vertex: */
+ const fi_type *src = save->buffer_map + prim->start * sz;
+ /* end of buffer: */
+ fi_type *dst = save->buffer_map + (prim->start + prim->count) * sz;
+
+ memcpy(dst, src, sz * sizeof(float));
+
+ prim->count++;
+ node->vertex_count++;
+ save->vert_count++;
+ save->buffer_ptr += sz;
+ save->vertex_store->used += sz;
+ }
+
+ if (!prim->begin) {
+ /* Drawing the second or later section of a long line loop.
+ * Skip the 0th vertex.
+ */
+ prim->start++;
+ prim->count--;
+ }
+
+ prim->mode = GL_LINE_STRIP;
+}
+
+